A technology for realizing three-dimensional display images by means of a projector that is capable of large-screen display has been developed and put to practical use. In three-dimensional image display by means of a projector, a parallax-based method is typically used in which a left-eye image and a right-eye image are projected onto a screen and the viewer views the left-eye image with his or her left eye and the right-eye image with his or her right eye.
In this method, the viewer must select the image corresponding to each eye. For that purpose, a polarization projector is known that uses polarized glasses to cause the viewer to select the image corresponding to each eye.
In the polarization projector, a left-eye image and a right-eye image that include parallax information are simultaneously displayed or are continuously and alternately displayed for each time-series frame on a screen such that the two images have different polarization state.
By viewing the displayed left-eye and right-eye images that have different polarization states through polarized glasses that have polarization selectivity, the viewer can visually sense the displayed images as a three-dimensional image because the two images are respectively and selectively observed with the corresponding eyes.
As a method of simultaneously displaying on a screen a left-eye image and a right-eye image having different polarization states, a method has been proposed that uses two projectors such that the left-eye image is displayed by the first projector and the right-eye image is displayed by the second projector. In this display method, in order to eliminate the inconvenience of providing two projectors that emit two types of projection light having different polarization states, two projectors are used that emit two types of projection light having the same polarization state, and a polarization switching element comprising a reflecting mirror is used to change the polarization state of the projection light from one projector, whereby the left-eye and right-eye images having different polarization states are generated by the two projectors.
In this method that uses two projectors, a problem occurs in which it is difficult both to match display image characteristics, such as brightness and color shade, of the two projectors and to adjust the projection positions of the two projectors. The use of two projectors also raises problems regarding miniaturization of the system and ease of use.
In this respect, Patent Literature 1 discloses a configuration in which a single projector is capable of displaying a left-eye image and a right-eye image. In this projector, a color wheel separates white light from a light source into red (R), green (G), and blue (B) in time division, and then a reflective polarizer separates the light into orthogonal linearly polarized light beams (P-polarization component and S-polarization component). The separated linearly polarized light beams are applied to different DMDs (Digital Micromirror Devices) as reflective light modulation elements to be modulated. The modulated linearly polarized light beams are synthesized by a polarization beam splitter and then enlarged and displayed by a single projection lens. This projector enables three-dimensional display by assigning the left-eye image and right-eye image to the two DMDs.